Both optical and thermal intramolecular electron transfer will be studied in specially synthesized systems with well separated, rigidly oriented "anisole" donors and Ru(III) acceptors with highly similar solid state and solution structures. Detailed studies of the anisole reaction results in Ru intramolecular charge-transfer spectra over a wide temperature range (4-300K) will be performed to evaluate the electron tunneling matrix element (using the Hush equation) and possibly identifying the electron-phonon coupling energies. Intramolecular thermal electron transfer rates will be measure by (collaborative) pulse radiolysis studies and related to the observed electronic coupling using the theories of Hopfield and Jortner. The orientation and separation of the donor/acceptor pair, driving force for electron transfer, and effects of solvent will be varied. This combination of detailed crystallographic, spectroscopic (solution and single-crystal), and dynamic studies on the specially constructed synthetic models has excellent potential to quantify important fundamental principles of long range electron transfer. These principles should be transferable to numerous biological systems in which long range electron transfer plays a crucial role.